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AA 757 Wing Delaminates During Flight, Makes News  
User currently offlineHaveBlue From United States of America, joined Jan 2004, 2098 posts, RR: 1
Posted (4 years 1 week 3 days 21 hours ago) and read 28955 times:

An AA 757 going from Miami to Orlando today was all over our local news because some delamination on the right wing near the leading edge progressively got worse during the short flight and was captured on camera by a passenger. Much ado about nothing but the news loved hyping up that they had the FAA investigating because of 'their' story.

http://www.wesh.com/news/24311656/detail.html


Here Here for Severe Clear!
68 replies: All unread, showing first 25:
 
User currently offlinewedgetail737 From United States of America, joined Aug 2003, 5890 posts, RR: 6
Reply 1, posted (4 years 1 week 3 days 21 hours ago) and read 28960 times:
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Luckily, it's only the leading-edge slat...and on the main part of the wing. It would be very hard for the main part of the wing to delaminate, since it's made with aluminum. But slats and flaps are typically composite.

User currently offlineCO777DAL From United States of America, joined Feb 2007, 598 posts, RR: 0
Reply 2, posted (4 years 1 week 3 days 20 hours ago) and read 28778 times:

Quoting wedgetail737 (Reply 1):
Luckily, it's only the leading-edge slat...and on the main part of the wing. It would be very hard for the main part of the wing to delaminate, since it's made with aluminum. But slats and flaps are typically composite.

Ummm... what about the 787? Isn't the whole wing composite? Can this happen on the 787m but on the main part of the wing? What about other parts of the plane? Can it delaminate if it is composite?



Worked Hard. Flew Right. Farewell, Continental. Thanks for the memories.
User currently offlinetdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 3, posted (4 years 1 week 3 days 16 hours ago) and read 27868 times:

Quoting CO777DAL (Reply 2):
Ummm... what about the 787? Isn't the whole wing composite?

What you're seeing in those photos is a honeycomb panel...two very thin composite skins wrapped over a honeycomb core. The skins aren't delaminating, the skins are separating from the core. The 787 wings aren't honeycomb, they're solid laminate.

Quoting CO777DAL (Reply 2):
Can this happen on the 787m but on the main part of the wing?

No. Different construction.

Quoting CO777DAL (Reply 2):
What about other parts of the plane?

Most of the 787 parts that were historically honeycomb panels are still honeycomb panels. Most of the parts that were solid aluminum are now solid laminate.

Quoting CO777DAL (Reply 2):
Can it delaminate if it is composite?

Composites can delaminate by separation between plies, but that's a different failure mode that what you're seeing in these photos.

Tom.


User currently offlineChrisNH From United States of America, joined Jun 1999, 4085 posts, RR: 2
Reply 4, posted (4 years 1 week 3 days 15 hours ago) and read 27572 times:

Quoting tdscanuck (Reply 3):
What you're seeing in those photos is a honeycomb panel...two very thin composite skins wrapped over a honeycomb core. The skins aren't delaminating, the skins are separating from the core. The 787 wings aren't honeycomb, they're solid laminate.

The term 'solid laminate' almost sounds like an oxymoron. To me, 'laminate' means several separate layers bonded into one, but they are individual layers nonetheless.


User currently offlinePITingres From United States of America, joined Dec 2007, 1124 posts, RR: 13
Reply 5, posted (4 years 1 week 3 days 14 hours ago) and read 27445 times:

Quoting ChrisNH (Reply 4):
The term 'solid laminate' almost sounds like an oxymoron.

"Solid" as opposed to "honeycomb".

Solid laminate has structure, but it's a unit (ideally) without voids. (Solid aluminum has structure too, the crystal grain!)



Fly, you fools! Fly!
User currently offlineaajfksjubklyn From United States of America, joined Jul 2007, 901 posts, RR: 1
Reply 6, posted (4 years 1 week 3 days 14 hours ago) and read 27207 times:

They should have put that silver tape on the damage-so visually it was not a concern. This is what I have witnessed on USAIR twice. It would have avoided a lot of media stupidity.

User currently offlineRL757PVD From United States of America, joined Dec 1999, 4646 posts, RR: 11
Reply 7, posted (4 years 1 week 3 days 13 hours ago) and read 27103 times:

I have to admit that even after having flown over 250,000 miles, that that sight would probably somewhat alarming to be enough to notify a f/a....


Experience is what you get when what you thought would work out didn't!
User currently offlineGBan From , joined Dec 1969, posts, RR:
Reply 8, posted (4 years 1 week 3 days 13 hours ago) and read 26904 times:

Quoting RL757PVD (Reply 7):
I have to admit that even after having flown over 250,000 miles, that that sight would probably somewhat alarming to be enough to notify a f/a

Same here with significantly more miles on the books  


User currently offlinemd80fanatic From United States of America, joined Apr 2004, 2660 posts, RR: 9
Reply 9, posted (4 years 1 week 3 days 12 hours ago) and read 25972 times:

The leading edge IS the main part of the wing. As little as a millimeter thick coating of ice here can reduce effective lift by almost 40%, even with slats stowed. Don't you think the rough (delaminated?) surface might just contribute (like rough ice does) to breaking the laminar flow of air over the leading edge (laminar flow here is wholly responsible for lift).

No, this is not good. Plans for landing should have been made the moment this was discovered. Also, this is NOT a place where speed tape should be used. For goodness sake, this zone on the wings needs to be as smooth as possible. Even a very thin coating of dirt on the leading edge results in lower lifting performance. Please folks, this is not aesthetic, this is serious business.


User currently offlinejetfuel From Australia, joined Jan 2005, 2206 posts, RR: 0
Reply 10, posted (4 years 1 week 3 days 12 hours ago) and read 25645 times:

Really the plane should have landed as a matter of emergency...


Where's the passion gone out of the airline industry? The smell of jetfuel and the romance of taking a flight....
User currently offlineaajfksjubklyn From United States of America, joined Jul 2007, 901 posts, RR: 1
Reply 11, posted (4 years 1 week 3 days 12 hours ago) and read 25649 times:

The flight can be accomplished in 30 minutes. Turning back to Miami or landing in Orlando would not have made much difference...

User currently offline474218 From United States of America, joined Oct 2005, 6340 posts, RR: 9
Reply 12, posted (4 years 1 week 3 days 12 hours ago) and read 24920 times:

Quoting wedgetail737 (Reply 1):
But slats and flaps are typically composite.


Actually the leading edge slats are made up of an aluminum outer skin, honeycomb (most likely nomex) core and an aluminum inner skin. This same construction is used on the spoilers. However, flaps are made up of aluminum structure consisting of skins, spars and ribs.

[Edited 2010-07-20 07:09:33]

[Edited 2010-07-20 07:10:04]

User currently onlineSPREE34 From United States of America, joined Jun 2004, 2241 posts, RR: 9
Reply 13, posted (4 years 1 week 3 days 12 hours ago) and read 24790 times:

Quoting jetfuel (Reply 10):
Really the plane should have landed as a matter of emergency...

No, it should not have. There was no danger here.

It would be like you emergency stopping your car because the anti dent strip on the door peeled off.



I don't understand everything I don't know about this.
User currently offlinejetfuel From Australia, joined Jan 2005, 2206 posts, RR: 0
Reply 14, posted (4 years 1 week 3 days 12 hours ago) and read 24568 times:

Quoting SPREE34 (Reply 13):
Quoting jetfuel (Reply 10):
Really the plane should have landed as a matter of emergency...

No, it should not have. There was no danger here.

It would be like you emergency stopping your car because the anti dent strip on the door peeled off.

Did the pilot(s) go and inspect the damage before deciding not to divert and land?? How do you know there was no danger?

A car is a silly analogy to try and draw. You know full well a car isn't 35,000 feet in the air. The fact is any wing component is part of a critical part of an airplane. If it was part of the interior cabin plastics we would accept that is not critical.

By suggesting there as no danger totally suggests that there is no risk that the damage could have got worse and reduced the airplanes performance envelope.



Where's the passion gone out of the airline industry? The smell of jetfuel and the romance of taking a flight....
User currently offlineSolarFlyer22 From US Minor Outlying Islands, joined Nov 2009, 990 posts, RR: 3
Reply 15, posted (4 years 1 week 3 days 12 hours ago) and read 24509 times:

Quoting ChrisNH (Reply 4):
The term 'solid laminate' almost sounds like an oxymoron. To me, 'laminate' means several separate layers bonded into one, but they are individual layers nonetheless.

They were several layers with different properties when constructed but after they have bonded, its almost like they have all melted together. I would imagine solid laminate is very hard to de-laminate as a result. The honeycomb stuff would be more prone since its glued together.

Even if 1 or 2 layers partially peeled off I doubt it would cause the part to fail.

Quoting aajfksjubklyn (Reply 11):
Quoting aajfksjubklyn (Reply 11):
The flight can be accomplished in 30 minutes. Turning back to Miami or landing in Orlando would not have made much difference...

Yeah, this route is really better suited to a train and if there is a problem its actually better to just keep going. You would lose momentum if you turned around.

Quoting md80fanatic (Reply 9):
The leading edge IS the main part of the wing. As little as a millimeter thick coating of ice here can reduce effective lift by almost 40%, even with slats stowed.

That doesn't seem accurate but I could be wrong. 40% of lift is a lot. I doubt the Pilots even noticed anything odd until they were told a/b the issue. Seems like a minor event to me. I'd be more concerned about AA maintenance. They should have caught this a long time ago when the part was weakening by doing tap tests.


User currently onlineSPREE34 From United States of America, joined Jun 2004, 2241 posts, RR: 9
Reply 16, posted (4 years 1 week 3 days 11 hours ago) and read 24214 times:

Quoting jetfuel (Reply 14):
You know full well a car isn't 35,000 feet in the air.

Really?! I had no idea.

Quoting jetfuel (Reply 14):
The fact is any wing component is part of a critical part of an airplane.

No, again. Any component is not "critical". Some components are critical, some are enhancements, some are mandated by regulatory agencies, some are marketing tools, some are light bulbs to illuminate the logo in the vertical stabilizer.



I don't understand everything I don't know about this.
User currently offlineMCO2BRS From United Kingdom, joined Jan 2007, 539 posts, RR: 0
Reply 17, posted (4 years 1 week 3 days 11 hours ago) and read 24218 times:

The flight was 37 minutes total, there wouldn't have been many options for diversion en-route except for MLB? I'm sure at that point it would have been more prudent to continue to destination than divert and have to deal with the logistics of getting pax, crew and aircraft to their destinations.

Cheers

MCO 2 BRS


User currently offlinejetfuel From Australia, joined Jan 2005, 2206 posts, RR: 0
Reply 18, posted (4 years 1 week 3 days 11 hours ago) and read 23949 times:

Quoting MCO2BRS (Reply 17):
The flight was 37 minutes total, there wouldn't have been many options for diversion en-route except for MLB? I'm sure at that point it would have been more prudent to continue to destination than divert and have to deal with the logistics of getting pax, crew and aircraft to their destinations.

This is true, as we don't know at what point the damage became evident. If they were already at cruise altitude it was likely that landing at MCO would be no longer a flight than finding an alternate



Where's the passion gone out of the airline industry? The smell of jetfuel and the romance of taking a flight....
User currently offlinesoon7x7 From , joined Dec 1969, posts, RR:
Reply 19, posted (4 years 1 week 3 days 11 hours ago) and read 23328 times:

Quoting CO777DAL (Reply 2):

Yes...it is a distinct possibility...But with the behavior of composites being better understood, lets hope more stringent inspection regs will be the norm.


User currently offlinesoon7x7 From , joined Dec 1969, posts, RR:
Reply 20, posted (4 years 1 week 3 days 11 hours ago) and read 22838 times:

Quoting md80fanatic (Reply 9):


The alloy leading edge still remained intact and that is the critical zone that encourages the airflow, while the aft end of the slat is fiberglass/nomex honeycomb, it does obviously improve the airflow but the evident degradation would not be enough to cause major issues as long as the alloy nose skin retained its integrity. Now if this damage hypothetically migrated to all the other adjoining wing slats on that wing, the pilots would have to deal with some asymmetrical disturbances. This problem I'm sure just did not happen instantaneously...most composite failures take a bit of time to get to the critical failure point excepting unusual loads...Close and thorough inspections will always high light problem areas in composites but they are tough to find. While the 787 does have honeycomb core construction, (all transports do)...the solid laminated CFRP is still prone to failure modes if imperfections during the manufacturing process go unnoticed and or internal delaminations occur. They can occur without suspicion resulting in catastrophic failure...g


User currently offlinesoon7x7 From , joined Dec 1969, posts, RR:
Reply 21, posted (4 years 1 week 3 days 10 hours ago) and read 22217 times:

Naturally, I just happened to have one that will help those to understand the construction...
Boeing slat construction

The image depicts a Typical Boeing construction configuration. This is a 747 Flap Slat, not a 757 leading edge slat. The difference being the 757 leading edge slat is about 35% alloy chordwise, the rest is the same as in the above photo. This material is common to all Boeing trailing edge surfaces, ailerons, flaps, slats, rudders, elevators, trim tabs...all nomex/ fibreglass...g


User currently offlineAirlineReporter From United States of America, joined Jun 2010, 78 posts, RR: 0
Reply 22, posted (4 years 1 week 3 days 10 hours ago) and read 21246 times:

This looks nasty, but I doubt it affected the safety of the air plane. Like others have stated, if the damage was on the front of the slat, this would be a different story. Even if it is not a safety issue, it still should be flying like that. There is no need for the passengers to have un-needed fear while flying and it makes a bad name for AA.

User currently offlineaajfksjubklyn From United States of America, joined Jul 2007, 901 posts, RR: 1
Reply 23, posted (4 years 1 week 3 days 10 hours ago) and read 20953 times:

The flight can be accomplished in 30 minutes. Turning back to Miami or landing in Orlando would not have made much difference...

User currently offlineTSS From United States of America, joined Dec 2006, 3066 posts, RR: 5
Reply 24, posted (4 years 1 week 3 days 10 hours ago) and read 20954 times:

A similar incident occurred last year on a flight departing LAX-
http://www.airliners.net/aviation-fo...general_aviation/read.main/4526728



Able to kill active threads stone dead with a single post!
25 Post contains images Goblin211 : The wing is a very strong structure like it is intended to be. if the leading edge was peeling off it seems to me no more serious than peeling paint.
26 soon7x7 : In the case of internal separation in the aft end of a slat, visual evidence may go unnoticed by even a trained eye unless someone on top of the wing
27 Jetsa : isnt the loss of lift due to the extra weight brought on by ice?
28 HaveBlue : Not at all, its from the airflow being disturbed and prematurely seperating from the wings surface to the irregularity of the ice formed there... thi
29 flybaurlax : No, ice is very rough and completely disrupts the airflow. Even though ice can appear to be very smooth, it has many impurities and degrades the lami
30 Post contains images soon7x7 : Actually if an aircraft is close to max gross, the extra ice weight especially on the tail feathers does not help the CG...but ice accumulation incre
31 AirNZ : What media stupidity are you referring to......or are you claiming that something not visually concerning has no cause for actual concern?
32 JoePatroni : Even frost (not to mention ICE) on the upper surface of the wing dramatically reduces the force of lift for that wing. Not because of extra weight bu
33 bikerthai : Correct me if I'm wrong, but isn't the leading edge slat deployed only on landing? So, the greatest aerodynamic load (greatest chance of additional fa
34 Arrow : There is no media stupidity here; they simply reported what happened, and used the guy's pictures. A.net folks have a great deal of contempt for medi
35 tonyban : If I saw this while sitting in the aircraft, I'd sh*t my pants. I have never seen this before !! This would have made me very uncomfortable.
36 DocLightning : I'm no pilot, but on every 757 flight where I've been able to see the leading edge, the slats are deployed for takeoff.
37 ruslan : Although I agree it isn't as bad as the media makes it out to be, I hope you folks would be rationalizing and thinking "outside the box" like that if
38 Post contains images HaveBlue : You are correct of course... I made a boo boo lol. Yes it does indeed increase the stall speed which is dangerous, not decrease it which would be a g
39 Santi319 : Leave it to AA for these things to happen
40 md80fanatic : No, the answer was well handled by several before me. Takeoff and landing ....... the problem comes in because the slats don't come out of the front
41 soon7x7 : The most important aspect of a wing whether in a dirty configuration or a clean configuration is the clean leading edge (the nose of the slat) and th
42 rfields5421 : Many of us - especially in the United States - deal with a 'solid laminate' every day. It is called plywood.
43 JoePatroni : This is very interesting. Thank you 7x7. I learned something today! JP
44 prebennorholm : The 757 has two separate slat panels on each wing, a short one between fuselage and engine, and a much longer one from the engine to the wing tip. Thi
45 frmrCapCadet : Very unhelpful analogy. A leading edge delaminating is not an everyday thing by any means.
46 soon7x7 : In todays current N/G designs, I feel your statement is correct...at least where primary structures are concerned. By the way...the 757 has four outb
47 soon7x7 : If you are familiar with the Lear 30 and 35 series jets, they had slow speed stability problems with the design so on the leadind edge which is a fix
48 dynamicsguy : The Boeing trailing edge surfaces we make are assemblies with carbon/Nomex or solid carbon components. That covers 777 rudder and elevators, 737 aile
49 prebennorholm : Thanks for the info, soon7x7, I didn't know that. That makes me rest a bit better on my next 757 flight. In fact I came back home on a 757 just 3 day
50 tu154m : It is the leading edge slat trailing edge wedge and there is already an AD issued on it for the 757, for the reasons the pictures the passengers took
51 474218 : McDonnell Douglas didn't "forget" they proved to the FAA that the DC-10 was controllable with asymmetrical slats during type certification. However,
52 soon7x7 : I thought if their wasn't an AD on them after this they might impose one...interesting...how long has the AD been in issue?
53 bikerthai : Does the AD give a clue on what to look for or the root of the problems? I've heard that early generation of glass/nomex honeycomb control surfaces t
54 474218 : Correct! Except the water and freezing causes de-lamination.
55 tu154m : The inspection process called out by the AD involves a close visual inspection, a "coin-tap" test(when you hit a delaminated spot, it sounds hollow).
56 Post contains images PRAirbus : AA 757s are getting old; some are over 20 years old!!! And tired too...
57 Post contains images soon7x7 : Boeing 747's were designed for roughly 85,000 hours of service yet many exceeded the 100,000 mark by a lot and are still doing so. Just keep replacing
58 tdscanuck : No, it's not. The main part of the wing is the front and rear spars and the upper and lower skins. Except for natural laminar flow (NLF) airfoils, wh
59 474218 : I just read the L-1011 SRM, Chapter 57-51-00 page 801 to 840 and found no "speed tape" approved repairs? Repairs using "speed tape" would be "tempora
60 tdscanuck : I should have been clearer there...current Western commercial manufacturers. SRM covers temporary repairs as well as permanent. Tom.
61 474218 : Sorry no temporary repairs. Negligible damage limits and permanent repairs only.
62 tdscanuck : I'm not sure what SRM you're looking at, but I'm staring 6 different ones that have temporary repairs in them. For damage tolerant structures, you ha
63 comorin : I didn't know that! I hate to impinge on your bandwidth, but could you kindly explain the concept a bit? I was always under the impression that turbu
64 Post contains links oldeuropean : To quote from an article about the other incident in August 09. The pilots then were more concerned about it than some armchair pilots here: http://cb
65 474218 : As I previously stated I it was the L-1011 SRM Chapter 57-51-00 (Leading Edge Slats) pages 801 through 840 (Pages 800 and above are detailed repairs)
66 tdscanuck : Turbulent flow, in the sense of airfoils, is all about the boundary layer. Are the air layers flowing smoothly over each other or do you have a bunch
67 comorin : Many thanks as always. In another thread, you had mentioned that most 'turbulence' experienced in flight was a result of gusts. Are the bumps due to
68 tdscanuck : Mostly lift changes. Gusts usually manifest as head or tailwind changes, which briefly alters the lift on the wing until either 1) the gust subsides
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